The present invention relates to a high output storage battery, more particularly to a lead-acid storage battery formed by uniting storage batteries having a plurality of cells.
There has been a growing demand for high output storage batteries as for backup power source in uninterruptive power supply units. A high output can be achieved by raising the voltage of storage battery. Research has been conducted to develop a storage battery that produces higher voltage than the conventional 6-volt or 12-volt storage battery. To raise the voltage, the cells connected in series have to be increased in number. One idea to achieve that is to connect a plurality of storage batteries by means of external wiring and to pack the storage batteries as by putting them in a metal or plastic case or strapping them by adhesive tape.
Such packing work involves troublesome external wiring and incurs expenses for packing materials and labor, resulting in an expensive storage battery. Another problem is that the storage battery thus obtained itself generates heat and goes up in temperature during discharging. Generally speaking, as the service temperature of the storage battery goes up, the cycle life will shorten. That is especially the case with the sealed lead-acid storage battery that fast falls in cycle life at high temperature. That is because of deterioration of the positive electrode plate exemplified by corrosion of the positive electrode grid and decrease of water in the electrolyte which are observed when the battery generates heat.
Attempts have been made to prevent the storage battery from deteriorating in performance because of heat generation. According to a method disclosed in Japanese Laid-Open Patent Publication No. Hei 8-27700, a necessary number of cell containers, one container housing one cell, are put together with some space left between them and are sealed with a common cover. In that arrangement, cooling space is secured around all the cells that make up a storage battery, especially a lead-acid storage battery. Through the space, the heat generated in the storage battery can be effectively dissipated. However, a fairly large number of cell containers are required to fabricate a storage battery with such a high output as needed in the market of late.
Another problem with that arrangement is that the connections between the cells are made over the cell container sidewalls. The intercell connectors that electrically connect the cells are sealed by adhesive in recesses provided on the inside surface of the container cover. The adhesive is also used to bond the cell containers and the container cover. In this arrangement, it is necessary to fill the adhesive into the recesses provided on the inside surface of the container cover for intercell connection and grooves for the battery container to fit into. If the number of cell containers is three or so, the filling work is not so troublesome. But to fabricate a 24-volt or higher output storage battery aimed at by the present invention, the number of cells required is not less than 12 in a lead-acid storage battery. In such a storage battery, the recesses and the fitting grooves are complicated, and it is very difficult to fill the adhesive in the recesses and grooves uniformly. As long as the cell containers are arranged in a row, it does not present serious problems. The problem is when cell containers are arranged in a plurality of rows. Especially, in case a battery is formed of three or more rows of cell containers, some cell containers are surrounded on all the four sides by the adjacent cell containers. In such a case, it is quite difficult to fit the container cover into the cell containers. That has been a problem in the manufacturing process.
Furthermore, in case a sealed storage battery according to this method is laid sideways, that is, in the fallen position, stress will concentrate in the bonded portion between the cell containers and the container cover and the joint portions provided on the cell containers. Since the cell container is formed of a single cell, the stress concentrated in the joint portions reaches the assembly element through the container sidewall. That is, the assembly element is forced to support the joint portions of the cell container in the cell compartment. That will have not only adverse effects on the characteristics of the storage battery but also decreases the strength of the plastic cell container, resulting in much deformation in the portion of the cell container side wall where the joint is provided and could cause micro cracks in the container. Such deformation of the cell container can cause extreme concentration of stress in the bonded portion between the cell container and the container cover, resulting in the separation of the bonded portion and affecting the liquid tightness and air tightness between the container and the container cover, thus greatly deteriorating the performance of the storage battery.
In view of the prior art described above, including the disadvantages and deficiencies of the prior art, an object of the present invention is to provide a high output storage battery with a high reliability that is easy to fabricate.
Another object of the present invention is to provide a storage battery that can be used in different positions such as an upright position and a fallen position.
A still another object of the present invention is to provide a storage battery especially of the 24-volt or 36-volt type.
The present invention provides a storage battery which comprises a plurality of monoblock containers put together with some space provided between them and a common container cover to close the openings of the monoblock containers, each monoblock container having a plurality of cell compartments separated from each other by partitions and each cell compartment housing an assembly element including positive and negative electrode plates stacked with separators placed between them.
The assembly element in each cell compartment of the monoblock container is electrically connected in series with the assembly element in the next cell compartment through the aperture provided in the partition between the cell compartments. At the ends of a block of assembly elements connected to each other are a pair of output terminalsxe2x80x94the positive electrode pole and the negative electrode pole.
In a preferred mode of the present invention, each monoblock container has two parallel cell rows of cell compartments, the cell compartments separated from each other by partition. Each cell row is formed of cell compartments arranged in one direction. The two cell rows of cell compartments are provided side by side in parallel. The respective monoblock containers are so positioned that the cell rows are in parallel with each other.
More particularly, the assembly elements of the respective cell rows in the monoblock container are electrically connected in series through aperturesxe2x80x94an aperture provided in the partition between the assembly elements in the adjacent cell compartments. In each container, the assembly element in the last cell compartment of the first cell row is connected in series to the assembly element in the cell compartment in the adjacent and corresponding position on the second cell row, also through an aperture provided in the partition between the two cell rows. The assembly element in the first cell compartment at the first end of one cell row has one positive electrode pole and the assembly element in the corresponding cell compartment on the other cell row has one negative electrode pole. The pair of the electrode poles permits the taking out of the output of the cells in the monoblock container. The container cover has a positive terminal connected to the positive electrode pole of the monoblock container at one end, a negative electrode terminal connected to the negative electrode pole of the monoblock container at the other end, and connectors that connect the positive electrode poles and the negative electrode poles of the neighboring monoblock containers.
In another preferred mode of the present invention, each monoblock container has one cell row including a plurality of cell compartments disposed in one direction and separated from each other by partitions. The respective monoblock containers are so arranged that the cell rows are in parallel with each other.
More specifically, the assembly element of each cell compartment of the monoblock container is electrically connected to the assembly element of the neighboring cell compartment through an aperture provided in the partition between them. The assembly element in the cell compartment at one end has a positive electrode pole while the assembly element in the cell compartment at the other end has a negative electrode pole. The container cover has a positive terminal connected to the positive electrode pole of the monoblock container at one end, a negative electrode terminal connected to the negative electrode pole of the monoblock container at the other end, and connectors that connect the positive electrode poles and the negative electrode poles of the neighboring monoblock containers.
The two ends of the connector are each connected to metal bushings insert molded to the container cover. One bushing is connected to the positive electrode pole of the monoblock container, while the other bushing is connected to the negative electrode pole of the neighboring monoblock container.
In a container having two cell rows, it is desirable that the stacking direction of the electrode plates of the assembly element is the same as the disposing direction of the cell rows. In the container having one cell row, it is preferable that the stacking direction of electrode plates of the assembly element is identical with the disposing direction of the cell compartments.
In a further preferred mode of the present invention, the monoblock container has a plurality of parallel ribs on the outside surface which form spaces between that monoblock container and the adjacent monoblock container. The spaces are for coolant to pass through.
In a still further preferred mode of the present invention, the monoblock container has a plurality of parallel ribs on the outside surface along the lines corresponding to the side ends of the aforesaid partitions, the parallel ribs forming spaces between that monoblock container and the adjacent monoblock container. The spaces are for coolant to pass through.
In still another preferred mode of the present invention, the monoblock container has projections at the lower right and left corners of the side face corresponding to the ends of the cell rows. One projection is linked with the projection of the adjacent monoblock container via a coupler having holes that fit over the projection. Thus, the adjacent monoblock containers are united.
In a further preferred mode of the present invention, the monoblock container has the ribs pressed against the corresponding ribs of the adjacent monoblock container. Thus the adjacent monoblock containers are united with each other via the ribs.
In still another preferred mode of the present invention, the monoblock container has a sealed chamber provided with openings communicating with the respective cell compartments, safety valves closing the respective openings in the sealed chamber, and an air passage having an explosion-proof mechanism through which the sealed chamber communicates with the outside.
While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings.